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<body class="manpage">
<div id="header">
<h1>
zmq_setsockopt(3) Manual Page
</h1>
<h2>NAME</h2>
<div class="sectionbody">
<p>zmq_setsockopt -
   set 0MQ socket options
</p>
</div>
</div>
<div id="content">
<div class="sect1">
<h2 id="_synopsis">SYNOPSIS</h2>
<div class="sectionbody">
<div class="paragraph"><p><strong>int zmq_setsockopt (void <em>*socket</em>, int <em>option_name</em>, const void <em>*option_value</em>, size_t <em>option_len</em>);</strong></p></div>
<div class="paragraph"><p>Caution: All options, with the exception of ZMQ_SUBSCRIBE, ZMQ_UNSUBSCRIBE,
ZMQ_LINGER, ZMQ_ROUTER_MANDATORY and ZMQ_XPUB_VERBOSE only take effect for
subsequent socket bind/connects.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="paragraph"><p>The <em>zmq_setsockopt()</em> function shall set the option specified by the
<em>option_name</em> argument to the value pointed to by the <em>option_value</em> argument
for the ØMQ socket pointed to by the <em>socket</em> argument. The <em>option_len</em>
argument is the size of the option value in bytes.</p></div>
<div class="paragraph"><p>The following socket options can be set with the <em>zmq_setsockopt()</em> function:</p></div>
<div class="sect2">
<h3 id="_zmq_sndhwm_set_high_water_mark_for_outbound_messages">ZMQ_SNDHWM: Set high water mark for outbound messages</h3>
<div class="paragraph"><p>The <em>ZMQ_SNDHWM</em> option shall set the high water mark for outbound messages on
the specified <em>socket</em>. The high water mark is a hard limit on the maximum
number of outstanding messages ØMQ shall queue in memory for any single peer
that the specified <em>socket</em> is communicating with.</p></div>
<div class="paragraph"><p>If this limit has been reached the socket shall enter an exceptional state and
depending on the socket type, ØMQ shall take appropriate action such as
blocking or dropping sent messages. Refer to the individual socket descriptions
in <a href="zmq_socket.html">zmq_socket(3)</a> for details on the exact action taken for each socket
type.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">ØMQ does not guarantee that the socket will accept as many as ZMQ_SNDHWM
messages, and the actual limit may be as much as 60-70% lower depending on the
flow of messages on the socket.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
messages
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1000
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_rcvhwm_set_high_water_mark_for_inbound_messages">ZMQ_RCVHWM: Set high water mark for inbound messages</h3>
<div class="paragraph"><p>The <em>ZMQ_RCVHWM</em> option shall set the high water mark for inbound messages on
the specified <em>socket</em>. The high water mark is a hard limit on the maximum
number of outstanding messages ØMQ shall queue in memory for any single peer
that the specified <em>socket</em> is communicating with.</p></div>
<div class="paragraph"><p>If this limit has been reached the socket shall enter an exceptional state and
depending on the socket type, ØMQ shall take appropriate action such as
blocking or dropping sent messages. Refer to the individual socket descriptions
in <a href="zmq_socket.html">zmq_socket(3)</a> for details on the exact action taken for each socket
type.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
messages
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1000
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_affinity_set_i_o_thread_affinity">ZMQ_AFFINITY: Set I/O thread affinity</h3>
<div class="paragraph"><p>The <em>ZMQ_AFFINITY</em> option shall set the I/O thread affinity for newly created
connections on the specified <em>socket</em>.</p></div>
<div class="paragraph"><p>Affinity determines which threads from the ØMQ I/O thread pool associated with
the socket&#8217;s <em>context</em> shall handle newly created connections.  A value of zero
specifies no affinity, meaning that work shall be distributed fairly among all
ØMQ I/O threads in the thread pool. For non-zero values, the lowest bit
corresponds to thread 1, second lowest bit to thread 2 and so on.  For example,
a value of 3 specifies that subsequent connections on <em>socket</em> shall be handled
exclusively by I/O threads 1 and 2.</p></div>
<div class="paragraph"><p>See also <a href="zmq_init.html">zmq_init(3)</a> for details on allocating the number of I/O
threads for a specific <em>context</em>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
uint64_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A (bitmap)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_subscribe_establish_message_filter">ZMQ_SUBSCRIBE: Establish message filter</h3>
<div class="paragraph"><p>The <em>ZMQ_SUBSCRIBE</em> option shall establish a new message filter on a <em>ZMQ_SUB</em>
socket. Newly created <em>ZMQ_SUB</em> sockets shall filter out all incoming messages,
therefore you should call this option to establish an initial message filter.</p></div>
<div class="paragraph"><p>An empty <em>option_value</em> of length zero shall subscribe to all incoming
messages. A non-empty <em>option_value</em> shall subscribe to all messages beginning
with the specified prefix. Multiple filters may be attached to a single
<em>ZMQ_SUB</em> socket, in which case a message shall be accepted if it matches at
least one filter.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_SUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_unsubscribe_remove_message_filter">ZMQ_UNSUBSCRIBE: Remove message filter</h3>
<div class="paragraph"><p>The <em>ZMQ_UNSUBSCRIBE</em> option shall remove an existing message filter on a
<em>ZMQ_SUB</em> socket. The filter specified must match an existing filter previously
established with the <em>ZMQ_SUBSCRIBE</em> option. If the socket has several
instances of the same filter attached the <em>ZMQ_UNSUBSCRIBE</em> option shall remove
only one instance, leaving the rest in place and functional.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_SUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_identity_set_socket_identity">ZMQ_IDENTITY: Set socket identity</h3>
<div class="paragraph"><p>The <em>ZMQ_IDENTITY</em> option shall set the identity of the specified <em>socket</em>
when connecting to a ROUTER socket. The identity should be from 1 to 255
bytes long and MAY NOT start with binary zero.</p></div>
<div class="paragraph"><p>If two clients use the same identity when connecting to a ROUTER, the
ROUTER socket shall accept only the first such client and reject the
others.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
NULL
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_REQ, ZMQ_REP, ZMQ_ROUTER, ZMQ_DEALER.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_rate_set_multicast_data_rate">ZMQ_RATE: Set multicast data rate</h3>
<div class="paragraph"><p>The <em>ZMQ_RATE</em> option shall set the maximum send or receive data rate for
multicast transports such as <a href="zmq_pgm.html">zmq_pgm(7)</a> using the specified <em>socket</em>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
kilobits per second
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
100
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using multicast transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_recovery_ivl_set_multicast_recovery_interval">ZMQ_RECOVERY_IVL: Set multicast recovery interval</h3>
<div class="paragraph"><p>The <em>ZMQ_RECOVERY_IVL</em> option shall set the recovery interval for multicast
transports using the specified <em>socket</em>. The recovery interval determines the
maximum time in milliseconds that a receiver can be absent from a multicast
group before unrecoverable data loss will occur.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Caution</div>
</td>
<td class="content">Exercise care when setting large recovery intervals as the data
needed for recovery will be held in memory. For example, a 1 minute recovery
interval at a data rate of 1Gbps requires a 7GB in-memory buffer.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
10000
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using multicast transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_sndbuf_set_kernel_transmit_buffer_size">ZMQ_SNDBUF: Set kernel transmit buffer size</h3>
<div class="paragraph"><p>The <em>ZMQ_SNDBUF</em> option shall set the underlying kernel transmit buffer size
for the <em>socket</em> to the specified size in bytes.  A value of zero means leave
the OS default unchanged. For details please refer to your operating system
documentation for the <em>SO_SNDBUF</em> socket option.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_rcvbuf_set_kernel_receive_buffer_size">ZMQ_RCVBUF: Set kernel receive buffer size</h3>
<div class="paragraph"><p>The <em>ZMQ_RCVBUF</em> option shall set the underlying kernel receive buffer size for
the <em>socket</em> to the specified size in bytes.  A value of zero means leave the
OS default unchanged. For details refer to your operating system documentation
for the <em>SO_RCVBUF</em> socket option.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_linger_set_linger_period_for_socket_shutdown">ZMQ_LINGER: Set linger period for socket shutdown</h3>
<div class="paragraph"><p>The <em>ZMQ_LINGER</em> option shall set the linger period for the specified <em>socket</em>.
The linger period determines how long pending messages which have yet to be
sent to a peer shall linger in memory after a socket is closed with
<a href="zmq_close.html">zmq_close(3)</a>, and further affects the termination of the socket&#8217;s
context with <a href="zmq_term.html">zmq_term(3)</a>. The following outlines the different
behaviours:</p></div>
<div class="ulist"><ul>
<li>
<p>
The default value of <em>-1</em> specifies an infinite linger period. Pending
  messages shall not be discarded after a call to <em>zmq_close()</em>; attempting to
  terminate the socket&#8217;s context with <em>zmq_term()</em> shall block until all
  pending messages have been sent to a peer.
</p>
</li>
<li>
<p>
The value of <em>0</em> specifies no linger period. Pending messages shall be
  discarded immediately when the socket is closed with <em>zmq_close()</em>.
</p>
</li>
<li>
<p>
Positive values specify an upper bound for the linger period in milliseconds.
  Pending messages shall not be discarded after a call to <em>zmq_close()</em>;
  attempting to terminate the socket&#8217;s context with <em>zmq_term()</em> shall block
  until either all pending messages have been sent to a peer, or the linger
  period expires, after which any pending messages shall be discarded.
</p>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (infinite)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</li>
</ul></div>
</div>
<div class="sect2">
<h3 id="_zmq_reconnect_ivl_set_reconnection_interval">ZMQ_RECONNECT_IVL: Set reconnection interval</h3>
<div class="paragraph"><p>The <em>ZMQ_RECONNECT_IVL</em> option shall set the initial reconnection interval for
the specified <em>socket</em>.  The reconnection interval is the period ØMQ
shall wait between attempts to reconnect disconnected peers when using
connection-oriented transports. The value -1 means no reconnection.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">The reconnection interval may be randomized by ØMQ to prevent
reconnection storms in topologies with a large number of peers per socket.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
100
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_reconnect_ivl_max_set_maximum_reconnection_interval">ZMQ_RECONNECT_IVL_MAX: Set maximum reconnection interval</h3>
<div class="paragraph"><p>The <em>ZMQ_RECONNECT_IVL_MAX</em> option shall set the maximum reconnection interval
for the specified <em>socket</em>.  This is the maximum period ØMQ shall wait between
attempts to reconnect. On each reconnect attempt, the previous interval shall be
doubled untill ZMQ_RECONNECT_IVL_MAX is reached. This allows for exponential
backoff strategy. Default value means no exponential backoff is performed and
reconnect interval calculations are only based on ZMQ_RECONNECT_IVL.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">Values less than ZMQ_RECONNECT_IVL will be ignored.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (only use ZMQ_RECONNECT_IVL)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_backlog_set_maximum_length_of_the_queue_of_outstanding_connections">ZMQ_BACKLOG: Set maximum length of the queue of outstanding connections</h3>
<div class="paragraph"><p>The <em>ZMQ_BACKLOG</em> option shall set the maximum length of the queue of
outstanding peer connections for the specified <em>socket</em>; this only applies to
connection-oriented transports. For details refer to your operating system
documentation for the <em>listen</em> function.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
connections
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
100
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_maxmsgsize_maximum_acceptable_inbound_message_size">ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size</h3>
<div class="paragraph"><p>Limits the size of the inbound message. If a peer sends a message larger than
ZMQ_MAXMSGSIZE it is disconnected. Value of -1 means <em>no limit</em>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int64_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_multicast_hops_maximum_network_hops_for_multicast_packets">ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets</h3>
<div class="paragraph"><p>Sets the time-to-live field in every multicast packet sent from this socket.
The default is 1 which means that the multicast packets don&#8217;t leave the local
network.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
network hops
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using multicast transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_rcvtimeo_maximum_time_before_a_recv_operation_returns_with_eagain">ZMQ_RCVTIMEO: Maximum time before a recv operation returns with EAGAIN</h3>
<div class="paragraph"><p>Sets the timeout for receive operation on the socket. If the value is <tt>0</tt>,
<em>zmq_recv(3)</em> will return immediately, with a EAGAIN error if there is no
message to receive. If the value is <tt>-1</tt>, it will block until a message is
available. For all other values, it will wait for a message for that amount
of time before returning with an EAGAIN error.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (infinite)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_sndtimeo_maximum_time_before_a_send_operation_returns_with_eagain">ZMQ_SNDTIMEO: Maximum time before a send operation returns with EAGAIN</h3>
<div class="paragraph"><p>Sets the timeout for send operation on the socket. If the value is <tt>0</tt>,
<em>zmq_send(3)</em> will return immediately, with a EAGAIN error if the message
cannot be sent. If the value is <tt>-1</tt>, it will block until the message is sent.
For all other values, it will try to send the message for that amount of time
before returning with an EAGAIN error.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (infinite)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_ipv4only_use_ipv4_only_sockets">ZMQ_IPV4ONLY: Use IPv4-only sockets</h3>
<div class="paragraph"><p>Sets the underlying native socket type.  A value of <tt>1</tt> will use IPv4 sockets,
while the value of <tt>0</tt> will use IPv6 sockets. An IPv6 socket lets
applications connect to and accept connections from both IPv4 and IPv6 hosts.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
boolean
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1 (true)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_delay_attach_on_connect_accept_messages_only_when_connections_are_made">ZMQ_DELAY_ATTACH_ON_CONNECT: Accept messages only when connections are made</h3>
<div class="paragraph"><p>If set to <tt>1</tt>, will delay the attachment of a pipe on connect until the underlying
connection has completed. This will cause the socket to block if there are no other
connections, but will prevent queues from filling on pipes awaiting connection.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
boolean
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (false)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_router_mandatory_accept_only_routable_messages_on_router_sockets">ZMQ_ROUTER_MANDATORY: accept only routable messages on ROUTER sockets</h3>
<div class="paragraph"><p>Sets the <em>ROUTER</em> socket behavior when an unroutable message is encountered. A
value of <tt>0</tt> is the default and discards the message silently when it cannot be
routed.  A value of <tt>1</tt> returns an <em>EHOSTUNREACH</em> error code if the message
cannot be routed.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_ROUTER
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_xpub_verbose_provide_all_subscription_messages_on_xpub_sockets">ZMQ_XPUB_VERBOSE: provide all subscription messages on XPUB sockets</h3>
<div class="paragraph"><p>Sets the <em>XPUB</em> socket behavior on new subscriptions and unsubscriptions.
A value of <em>0</em> is the default and passes only new subscription messages to
upstream. A value of <em>1</em> passes all subscription messages upstream.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_XPUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_keepalive_override_so_keepalive_socket_option">ZMQ_TCP_KEEPALIVE: Override SO_KEEPALIVE socket option</h3>
<div class="paragraph"><p>Override <em>SO_KEEPALIVE</em> socket option(where supported by OS).
The default value of <tt>-1</tt> means to skip any overrides and leave it to OS default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1,0,1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_keepalive_idle_override_tcp_keepcnt_or_tcp_keepalive_on_some_os">ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPCNT(or TCP_KEEPALIVE on some OS)</h3>
<div class="paragraph"><p>Override <em>TCP_KEEPCNT</em>(or <em>TCP_KEEPALIVE</em> on some OS) socket option(where supported by OS).
The default value of <tt>-1</tt> means to skip any overrides and leave it to OS default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1,&gt;0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_keepalive_cnt_override_tcp_keepcnt_socket_option">ZMQ_TCP_KEEPALIVE_CNT: Override TCP_KEEPCNT socket option</h3>
<div class="paragraph"><p>Override <em>TCP_KEEPCNT</em> socket option(where supported by OS).
The default value of <tt>-1</tt> means to skip any overrides and leave it to OS default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1,&gt;0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_keepalive_intvl_override_tcp_keepintvl_socket_option">ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option</h3>
<div class="paragraph"><p>Override <em>TCP_KEEPINTVL</em> socket option(where supported by OS).
The default value of <tt>-1</tt> means to skip any overrides and leave it to OS default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1,&gt;0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_accept_filter_assign_filters_to_allow_new_tcp_connections">ZMQ_TCP_ACCEPT_FILTER: Assign filters to allow new TCP connections</h3>
<div class="paragraph"><p>Assign arbitrary number of filters that will be applied for each new TCP transport
connection on a listening socket.
If no filters applied, then TCP transport allows connections from any ip.
If at least one filter is applied then new connection source ip should be matched.
To clear all filters call zmq_setsockopt(socket, ZMQ_TCP_ACCEPT_FILTER, NULL, 0).
Filter is a null-terminated string with ipv6 or ipv4 CIDR.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
no filters (allow from all)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all listening sockets, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_return_value">RETURN VALUE</h2>
<div class="sectionbody">
<div class="paragraph"><p>The <em>zmq_setsockopt()</em> function shall return zero if successful. Otherwise it
shall return <tt>-1</tt> and set <em>errno</em> to one of the values defined below.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_errors">ERRORS</h2>
<div class="sectionbody">
<div class="dlist"><dl>
<dt class="hdlist1">
<strong>EINVAL</strong>
</dt>
<dd>
<p>
The requested option <em>option_name</em> is unknown, or the requested <em>option_len</em> or
<em>option_value</em> is invalid.
</p>
</dd>
<dt class="hdlist1">
<strong>ETERM</strong>
</dt>
<dd>
<p>
The ØMQ <em>context</em> associated with the specified <em>socket</em> was terminated.
</p>
</dd>
<dt class="hdlist1">
<strong>ENOTSOCK</strong>
</dt>
<dd>
<p>
The provided <em>socket</em> was invalid.
</p>
</dd>
<dt class="hdlist1">
<strong>EINTR</strong>
</dt>
<dd>
<p>
The operation was interrupted by delivery of a signal.
</p>
</dd>
</dl></div>
</div>
</div>
<div class="sect1">
<h2 id="_example">EXAMPLE</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">Subscribing to messages on a <em>ZMQ_SUB</em> socket</div>
<div class="content">
<pre><tt>/* Subscribe to all messages */
rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "", 0);
assert (rc == 0);
/* Subscribe to messages prefixed with "ANIMALS.CATS" */
rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "ANIMALS.CATS", 12);</tt></pre>
</div></div>
<div class="listingblock">
<div class="title">Setting I/O thread affinity</div>
<div class="content">
<pre><tt>int64_t affinity;
/* Incoming connections on TCP port 5555 shall be handled by I/O thread 1 */
affinity = 1;
rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &amp;affinity, sizeof affinity);
assert (rc);
rc = zmq_bind (socket, "tcp://lo:5555");
assert (rc);
/* Incoming connections on TCP port 5556 shall be handled by I/O thread 2 */
affinity = 2;
rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &amp;affinity, sizeof affinity);
assert (rc);
rc = zmq_bind (socket, "tcp://lo:5556");
assert (rc);</tt></pre>
</div></div>
</div>
</div>
<div class="sect1">
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="paragraph"><p><a href="zmq_getsockopt.html">zmq_getsockopt(3)</a>
<a href="zmq_socket.html">zmq_socket(3)</a>
<a href="zmq.html">zmq(7)</a></p></div>
</div>
</div>
<div class="sect1">
<h2 id="_authors">AUTHORS</h2>
<div class="sectionbody">
<div class="paragraph"><p>This ØMQ manual page was written by Martin Sustrik &lt;<a href="mailto:sustrik@250bpm.com">sustrik@250bpm.com</a>&gt; and
Martin Lucina &lt;<a href="mailto:mato@kotelna.sk">mato@kotelna.sk</a>&gt;.</p></div>
</div>
</div>
</div>
<div id="footnotes"><hr /></div>
<div id="footer">
<div id="footer-text">
ØMQ 3.2.5<br />
Last updated 2014-03-25 15:21:52 CET
</div>
</div>
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